Tuned circuits of wireless apparatus



Feb. 7, 1928. 1,658,718

H. HARDCASTLE -TUNED CIRCUITS OF WIRELESS APPARATUS Filed Dec. 5, 1925 Ha/dfff/e Paiement; .7,1928' V i 1,658,718'l UNIT-ED Islra'rrzs PATENT ori-icaA HARRY HARIICASTL, `Olli' WELLINGTON, NEW ZEALAND.

TUNED CIRCUITS OF WIRELESS APPARATUS. i I Application filed December 3, 1925, Serial No. 76,026, and in New Zealand November 5, 1925.

'lhis invention-relates to wireless appapreferably it is connected tothe high poten- 'ratus of the type employing tuned oscillatory tial sides, and in the latter case the earth circuits, which in order to enable the appotential terminals of all the condensers 2, paratus to function correctly, requires .to 2a, 2b, 2, may be joined together and the v be tuned to one or more definite frequencies common connection Staken to some part of 60 of electrical. oscillation. l 'the apparatus at earth potential.

The tuning or adjustment of such c1r. In such a group of pre-tuned condensers, cuits as before mentioned is a critical operathe high; potential terminals of the condention attended in a great many cases by obsers are connected each to the separate switch 10 jectionable results, and it is an object 0f point 5a, 5b, 5, 5d, the selector switch 6 be- 65 this invention to provide improvements ing mounted so as to be capable of being which will enable such tuning or adjustment moved across said points, to contact with any to be carried out quickly, easily, and accuselected one thereof, and place the condenser rately, and without the objectionable results, electrically connected with the selected point, mostly, or at least frequently associated with actively in the circuit. l70 Said tuning or adjusting operation. Vhen more than one tuned circuit each as The invention consists in placing in a before described is being utilized (see Figure tuned circuit of a wireless apparatus, a se- 2) the selector switches 6 can be mounted on ries of condensers cach pre-tuned in conjunca single device 9, operated by a single conzo tion with the inductance in the circuit, to trol handle 10, or said switches 6, may be a pre-determined frequency, any one f said separately placed' and connected together by condensers being capable by the use of a any convenient mechanical means which will selector switch, of being actively incorporenable them to be operated fromv a single ated in said tuned circuit, so as to tune or control or as one unit.

sa adjust the latter to a selected frequency. Also in the last described arrangement, N

This arrangement enables the circuit to flexible or equivalent connections 11 are used be permanentlyprovided with a number of between the switches 6 and the tuners. differentcapacities any one of which can ylhe condensers employed can be of any v be instantly utilized to tune the circuit to a suitable type sumciently small to enable them :w selected frequency, the frequencies available to be incorporated in the required numbers B5 in the circuit being determined by the variand fitted with means for adjusting their ous capacities of the condensers placed capacities and having 'the character of pertherein. manence of adjustment.

ln the drawings, Figure. 1 illustrates dialn order to compensate for small varia- 35 grammatically one form of 'my invention, tions from accurate tuning, vernier condon- 90 while Figure 2 illustrates diagrammatically sers may be associated with each circuit.

a modified form. l When series of condensers arranged and ln the diagram forming Figure 1 of the adapted to be utilized as aforesaid, are used accompanying drawing 1, represents an inin conjunction with continuously variable lo ductance; 2, 2a, 2b, and 2", a series of concondensers, the earth potential sides of the 95 densers each pretuned in conjunction with latter can be connected to the earth potential the inductance 1 to a predetermined fresides of the other condensers and the high quency; 8, a variable condenser; 4, a small potential sides of the variable condensers 6 series condenser for converting the variable to switch points 5 so-that the selector switch 45 condenser into a vernier control; 5 a switch 6 can be made to cutout the pre-tuned con! 100 point electrically connected with the variable dansers 2, `2a, 2, 2, and switch in the varicondenser 3; 5a, 5b, 5, and, switch points able condensers 3. j electrically connected, each with one of the Also when' a continuously variable condenpretuned condensers 2, 2a, 2b and 2; 6, a ser is used in conjunction with, pre-tuned 50 selector switch; 7 the lead to the grid of a condensers, the former may be utilized as a 105 valve, or a crystal detector; and 8 the lead vernier control for the pre-tuned condensers to earth. y by placing a small condenser 4c in series with The selector switch 6, may be connected to the variable condenser between the high poeither the high potential or the earth potentential side of the latter, and the selector 5 tial sides ofthe condensers 2, 2a, 2", 2, .but switch 6, whereby the variable condenser u will have its effective capacity reduced to a value controlled by the capacity of the small condenser 4.

The apparatus described may be associated with means controlled by the saine switch control, for introducing additional or alternative inductances, to extend the frequency 'range of the apparatus.

a switching system by which an of the condensers in the group can be su stituted for the ordinary variable condenser in circuit to tune the circuit to 'a frequency determined by the setting of the condenser so connected. and

in association with said usual variable condenser, a series condenser so connected that it and said usual condenser remain connected in parallel with each of the condensers functioning in place of the usual condenser, the L latter condenser being then available as a line adjusting device.

In testimony whereof I have signed my name to this specification. HARRY HARDGASTLE. 

